Integrated process for optimum production of para-xylene

Abstract

A method of producing p-xylene comprising the steps of separating the reformate feed in the reformate splitter to produce a benzene stream, a combined heavy stream, a xylene stream, and a toluene stream, converting the C9+ aromatic hydrocarbons in the presence of a dealkylation catalyst in the dealkylation reactor to produce a dealkylation effluent, separating the dealkylation effluent in the dealkylation splitter to produce a C9 stream and a C10+ stream, reacting the C9 stream, the toluene stream, the benzene stream, and the hydrogen stream in the presence of a transalkylation catalyst in the transalkylation reactor to produce a transalkylation effluent, separating the p-xylenes from the xylene stream in the p-xylene separation unit to produce a p-xylene product and a p-xylene depleted stream, converting the m-xylene and o-xylene in the p-xylene depleted stream in the isomerization unit to produce an isomerization effluent.

That which is claimed is: 
     
       1. A system for producing para-xylene (p-xylene) from a reformate feed, the system comprising:
 a reformate splitter, the reformate splitter configured to separate the reformate feed, wherein the reformate feed comprises aromatic hydrocarbons, wherein the aromatic hydrocarbons are selected from the group consisting of benzene, toluene, mixed xylenes, carbon-nine plus (C9+) aromatic hydrocarbons, and combinations of the same, wherein the reformate splitter produces a light gases stream, a combined heavy stream, a benzene stream, a xylene stream, and a toluene stream, wherein the combined heavy stream comprises the C9+ aromatic hydrocarbons, and wherein the xylene stream comprises the mixed xylenes, wherein the mixed xylenes comprises p-xylenes; 
 a dealkylation reactor fluidly connected to the reformate splitter, the dealkylation reactor configured to convert the C9+ aromatic hydrocarbons to carbon-six (C6) to carbon-eight (C8) aromatic hydrocarbons in the presence of a dealkylation catalyst to produce a dealkylation effluent, wherein the dealkylation reactor is at a dealkylation temperature, wherein the dealkylation reactor is at a dealkylation pressure, wherein the dealkylation effluent comprises aromatic hydrocarbons such that an amount of C9+ aromatic hydrocarbons in the dealkylation effluent is less than the amount of C9+ aromatic hydrocarbons in the reformate feed; 
 a dealkylation splitter fluidly connected to the dealkylation reactor, the dealkylation splitter configured to separate the dealkylation effluent to produce a light recycle stream, a C10+ aromatics stream, and a C9 stream; 
 a transalkylation reactor fluidly connected to the dealkylation reactor and fluidly connected to the reformate splitter, the transalkylation reactor configured to convert toluene and C9 aromatic hydrocarbons in the presence of a transalkylation catalyst to produce a transalkylation effluent, wherein the transalkylation reactor is at a transalkylation temperature, wherein the transalkylation reactor is at a transalkylation pressure, wherein the toluene is supplied by a toluene split stream, wherein the toluene split stream is separated from the toluene stream, wherein the transalkylation catalyst is operable to catalyze transalkylation reactions, wherein the transalkylation effluent comprises C6 to C9+ aromatic hydrocarbons; 
 a p-xylene separation unit fluidly connected to the reformate splitter, the p-xylene separation unit configured to separate p-xylenes from the xylene stream to produce a p-xylene product and a p-xylene depleted stream, wherein the p-xylene product comprises p-xylenes, wherein the p-xylene depleted stream comprises meta-xylene (m-xylene) and ortho-xylene (o-xylene); and 
 an isomerization unit fluidly connected to the p-xylene separation unit, wherein the isomerization unit is configured to convert the m-xylene and o-xylene in the p-xylene depleted stream to produce an isomerization effluent, wherein the isomerization unit is at an isomerization temperature, wherein the isomerization unit is at an isomerization pressure, wherein the isomerization effluent comprises C8 aromatic hydrocarbons. 
 
     
     
       2. The system of  claim 1 , wherein a volumetric flow rate of the toluene split stream is operable to maintain a volume ratio of toluene to trimethylbenzene in the transalkylation reactor in a range of 0.3 to 3. 
     
     
       3. The system of  claim 1 , wherein the dealkylation temperature is between 200° C. and 550° C., further wherein the dealkylation pressure is between 5 bar and 50 bar, and wherein a liquid hourly space velocity in the dealkylation reactor is between 1 hr −1  and 20 hr −1 . 
     
     
       4. The system of  claim 1 , wherein the transalkylation temperature is between 200° C. and 550° C., further wherein the transalkylation pressure is between 10 bar and 50 bar, and wherein a liquid hourly space velocity in the transalkylation reactor is between 0.2 hr −1  and 20 hr −1 . 
     
     
       5. The system of  claim 1 , wherein the isomerization temperature is between 200° C. and 550° C., further wherein the isomerization pressure is between 5 bar and 50 bar, and wherein a liquid hourly space velocity in the isomerization unit is between 1 hr −1  and 20 hr −1 . 
     
     
       6. The system of  claim 1 , further comprising a toluene disproportionation reactor fluidly connected to the reformate splitter, the toluene disproportionation reactor configured to convert a fraction of the toluene from the toluene stream to produce a disproportionation effluent, wherein the disproportionation effluent comprises C6 to C8 aromatic hydrocarbons.